The Cornerstone Program was established in 2000 to promote multi-family development for both rental and homeownership. The Cornerstone program offers developers the opportunity to bid on the opportunity to build apartments on city-owned land. Initially 21 clusters of vacant city-owned lots, including eight clusters in East and Central Harlem, nine in Brooklyn, and four in the Bronx were transferred. A minimum of 20 percent of the apartments built were to benefit low-income residents. Proposals that provided the greatest mix of affordability using the least amount of subsidy received preference.